July 2003 Sky from the Keeble Observatory
Mars, here we come! Earth orbits closer to the Sun, and moves
faster than Mars, so we're about to lap the red planet . at opposition
in late August, a mere 34.6 million miles will separate us. Mars
will rise earlier and earlier each night, until on August 28 it
will rise as the Sun is setting. Since the approach to opposition
is the ideal time to launch probes to Mars, it should be no surprise
that several are on their way (and another is preparing for launch,
perhaps on the 2nd of July). They all hope to join Mars Global Surveyor
and 2001 Mars Odyssey, which have been orbiting Mars since 1998
and 2001, respectively. All should be arriving in December or January.
Hope is the translation of the name of a Japanese probe, Nozomi.
Hope is also faint for the success of this mission. Launched in
1998 July, it was supposed to arrive at Mars in October of the same
year. However, its trajectory was flawed and controllers burned
too much fuel trying to adjust. They adopted a strategy of using
Earth as a gravitational slingshot to boost its orbit toward Mars.
The latest maneuver in mid-June sent it on its final trajectory,
but the spacecraft is still in trouble. A solar flare last April
shorted out part of its circuitry, in particular the heating and
communications systems were compromised. Controllers are attempting
to reprogram on-board computers to correct for these problems.
Mars Express is the European Space Agency's entry, launched on
3 June and expected to arrive on Christmas day. The orbiter will
study the surface, mapping minerals and producing a high-resolution
stereo image of the surface, able to see features between 2 and
10 meters in size. Another instrument will use penetrating radar
to study the subsurface structure of the planet to a depth of 2
Hitching a ride with Mars Express is the British lander called
Beagle 2. This small probe (a mere 65 kilograms . 143 pounds) will
use a parachute and airbag landing system similar to 1997's successful
Pathfinder probe. It will drill into the surface some 2 meters,
looking for signs of water and/or life. Most of the instruments
are deployed at the end of a robot arm. A camera will take images
of the surroundings, as well as providing close-up views of Martian
rocks and soil. A wire-guided mole will dig under rocks, and a
grinding tool will be used to remove surface layers from rock samples
to better study their interiors. The probe is ambitious, as Britain's
first entry into Mars exploration, but its small size precluded
building any redundancy into its systems. If anything goes wrong,
the mission will likely fail.
NASA is sending two rovers, named Spirit and Opportunity (more
formally, Mars Exploration Rovers A and B) to opposite sides of
the planet. These are more sophisticated than Beagle 2, essentially
upgrades of the Sojourner rover which accompanied Pathfinder. At
170 kilograms and about the size of a small desk, they are nearly
three times the size They will also use the airbag system to land.
Their instruments include cameras, drills, and microscopes. They
should ramble several dozen meters each Martian day, sampling rocks
and soil and returning spectacular images from the surface. Spirit
is already underway, launched on the 10th of June. Opportunity is
slated for launch on the 28th of June.
For more information about these Mars probes, point your web browser
Lunar phases for 2003 July: First Quarter on the 6th, at 10:33
pm; Full on the 13th, at 3:22 pm; Last Quarter on the 21st, at 3:02
am; New Moon on the 29th, at 2:54 am.
Saturn passes behind the Sun and moves into the morning sky as
Venus vanishes into the Sun's glare, emerging from twilight by month's
end. Mercury also swings behind the Sun, moving into the evening
sky and joining Jupiter in the west later in the month. As noted
above, Mars rises earlier each night - midnight at the beginning
of July, about 10:30 by the end of the month. It will become brighter
and brighter as we approach opposition in late August. Even small
telescopes will begin to pick out surface features, like the polar
Looking overhead about an hour after sunset, you'll see the zenith
point bracketed by bright Arcturus (about 30 degrees toward the
southwest) and Vega (about the same angle from zenith, but towards
the east). The trapezoidal shape of Hercules is the closest familiar
constellation, about halfway toward Vega. Binoculars and a clear
night may permit you to see the great globular cluster M13 just
inside the northwest corner of Hercules. Low to the west, Leo and
bright Regulus accompany the setting of Jupiter and bid farewell
until late fall. To the southwest is the bright star Spica, in Virgo.
Almost due south is bright red Antares - rival of Mars - but don't
be confused, Mars rises later, to the southeast. The summer triangle
is now about halfway to zenith from the eastern horizon. Vega is
at the top, Altair to the southeast, and Deneb to the northeast.
From Vega, shift your binoculars or small telescope to the next
star below in Lyra - you'll see that it is actually four stars,
known as the double double. Now shift below and to the right.
Between the two stars marking the other end of the Lyre, you may
see the faint circle of the Ring Nebula. Our own Sun will probably
look like this in another 6 billion years. From Deneb, in Cygnus,
sweep your binoculars to the right along the neck of the Swan.
The last star you see in the head is Albireo, a beautiful binary
with stars of orange and blue.
For your own monthly star chart, you can direct your web browser
You will find extensive descriptions of what's worth looking for,
and you can download and print a single copy for your personal use.